Abstract:Glial cells are a large group of cells in the nervous system that are distinct from neurons and are 10-50 times more numerous. For a long time glial cells were considered a kind of "glue" in the nervous system, only to bind neurons and fill the nervous system. As neuroscience has advanced in recent decades, neurobiologists have discovered that glial cells perform a variety of functions and are involved in higher functions such as memory, cognition, neurodevelopmental and neurodegenerative diseases, and even aging. According to PubMed, the 10-year growth rate of glial cell related papers in China is 270%, much higher than the global average growth rate of 140%, indicating that the research momentum of glial cells in China is very strong. This issue of Progress in Biochemistry and Biophysics has features more than 19 papers on glial cells. It covers the aspects of physiological and pathological functions of glial cells. The publication of this issue will promote the scientific research on glial cells in China and serve as a reference for the China Brain Project.

Abstract:Cellular conversion is a process of genetic reprogramming by various methods to induce the direct transformation of one type of cell into another without going through other intermediate states. Neuronal loss is a common pathological process in a variety of neurological disorders, including Parkinson’s disease, Alzheimer’s disease, and stroke. Neuronal loss is usually irreversible and causes motor, sensory, and psychiatric symptoms. Since the human central nervous system has limited capacity for neuronal regeneration, therapeutic strategies that use glial cells (astrocytes, microglia, and oligodendrocyte precursor cells) to transdifferentiate into functional neurons in situ of neuronal loss and integrate them into neural networks have received much attention. In recent years, successful conversion of glia-to-neuron by manipulating the gene expression of key transcription factors in neuronal fate determination in glial cells has been discovered. Nevertheless, there is still some controversy about the scientific validity of some research technologies, the rationality of judgment criteria, and the self-consistency between experimental results and conclusions. This article reviews the discovery and development of glia-to-neuron conversion and takes astrocytes, microglia, and oligodendrocyte progenitor cells as examples to summarize the important findings of glia-to-neuron conversion with discussion and perspective.

Abstract:Leukoencephalopathy with vanishing white matter (VWM) is an autosomal recessive leukoencephalopathy caused by any of EIF2B 1-5 mutations, encoding five subunits α-ε of eukaryotic translation initiation factor 2B (eIF2B). The clinical phenotype of the disease varies greatly. The typical manifestation is progressive motor function regression, which can be accompanied by ataxia and epilepsy and susceptible to episodic aggravation of stress such as fever and trauma. Imaging showed progressive liquefaction of cerebral white matter. Autopsy neuropathology is characterized by extensive white matter sparseness and cystic degeneration, no reactive proliferation of glial cells, abnormal astrocyte morphology, overexpression of progenitor cell markers Nestin and GFAPδ, and increased number of oligodendrocyte precursor cells and decreased mature oligodendrocytes, foamed and increased apoptosis. The VWM gene EIF2B 1-5 is housekeeping gene, but most patients usually only have white matter involvement. A small number of fetal and early infantile patients may have multisystem involvement, and adult female patients may have ovarian dysfunction. It is currently believed that astrocytes play a central role in the pathogenesis of VWM. Pathological astrocytes cause secondary oligodendrocyte maturation disorder and abnormal myelination, which in turn lead to white matter lesions. Other disease mechanisms, including excessive activation of the unfolded protein response (UPR) after endoplasmic reticulum stress, mitochondrial dysfunction, and autophagy inhibition, are not fully understood.

Abstract:Metachromatic leukodystrophy (MLD) is a rare hereditary leukoencephalopathy caused by arylsulfatase A (ARSA) gene mutation. There are individual differences in the clinical manifestations and disease progression speed of MLD, but almost all patients will eventually have complete loss of motor and cognitive functions. Clinically, patients are divided into late infantile onset, juvenile onset and adult onset according to their age of onset and severity of illness. The clinical diagnosis of MLD includes progressive neurological regression and typical magnetic resonance imaging (MRI) findings. Its clinical manifestations are similar to many diseases, and it needs to be differentiated from other leukoencephalopathies and lysosomal storage diseases. There is no effective treatment for MLD. Hematopoietic stem cell transplantation or bone marrow transplantation, enzyme replacement therapy and gene therapy are the research hotspots of MLD treatment. At present, only symptomatic support treatment can be carried out for patients. Recent studies have found that intrathecal injection of recombinant human arylsulfatase A (rhASA) could delay the progress of the disease. Effective prenatal molecular diagnosis for MLD families is the main method to prevent the occurrence of MLD.

Abstract:Pelizaeus-Merzbacher disease (PMD) is the most common disease of hypomyelination disorder. Most of the patients displayed with development delay especially motor delay, nystagmus and hypotonia, and so on. PMD is caused by the pathological changes of oligodendrocyte cell, which end up with hypomyelination disorder. Previous studies have demonstrated PLP1 point mutation affects the survival of oligodendrocytes and the formation of myelin molecular structure by affecting the formation of PLP1/DM20 oligomerization: PLP1 duplication stops oligodendrocyte and myelin development. Recent studies on organelle interaction network (OIN) have further demonstrated the pathogenic mechanism of PLP1 mutations: point mutations impact oligodendrocyte myelination by affecting the trafficking of PLP1 mutants to the plasma membrane. While PLP1 duplication had closer ER-mitochondrion interfaces named mitochondria-associated membranes (MAMs). These changes in both the ER and mitochondria then led to mitochondrial dysfunction. At present, relevant studies have shown that some small molecular compounds or drugs such as cholesterol, piracetam and gene therapy can improve the clinical symptoms of PMD in animals, and their efficacy in PMD patients needs to be further confirmed.

Abstract:Enteric glial cells are distributed in the mucosa, submucosa and muscular layer of the digestive tract, and are characterized by extensive heterogeneity and plasticity. The mucosal layer is most close to the intestinal cavity and vulnerable to pathogen and inflammation, thus mucosal homeostasis has attracted much attention. Mucosal enteric glial cells (mEGCs) have complex interactions with intestinal epithelial cells, vascular endothelial cells, immune cells and other nonneuronal cells. From the perspective of structure and function, the intestinal glial cells may be in a central regulatory position. Recent studies have continuously revealed mEGCs subtypes and new functions, indicating that mEGCs has functional changes under pathological conditions. It is critical to understand how mEGCs cause mucosal dysfunction and their role in disease development. This article will summarize the role of mEGCs in maintaining mucosal homeostasis and regulating inflammation.

Abstract:Megalencephalic leukoencephalopathy (MLC) with subcortical cysts is a degenerative disease of the central nervous system caused by mutations in MLC1 or GlialCAM, characterized with astrocyte swelling and vesicle formation of myelin. MLC/GlialCAM and ClC-2 co-localize at the end feet of astrocytes. Previous studies discovered that MLC1/GlialCAM mutation affects the conductivity of ClC-2 channels, resulting in the imbalance of water and ion homeostasis in astrocytes, while in the GlialCAM homozygous knockout mouse, the phenotype cannot be rescued by crossing with transgenic mice that selectively open ClC-2. Recent study showed that mutated MLC1 promotes the internalization of Connexin43 and reduced the formation of gap junctions at the cell membrane, affected the efficiency of intercellular communication, and interrupted normal glial syncytial function, which led to MLC with astrocyte edema and the vesicle formation of myelin. It indicated that the abnormal function of glial syncytia composed of astrocytes, oligodendrocytes and connexins needs further investigation.

Abstract:Spinal cord astrocytoma is a rare malignant tumor of the central nervous system, with unique characteristics in epidemiology, clinical tumor phenotype, molecular genetic markers, and therapeutic research. With the development of surgical techniques and molecular pathology, significant progress has been made in the research and treatment of brain glioma. However, there are only limited advances in the research and treatment of spinal cord astrocytoma. The potential cautions include: (1) it is difficult to carry out research because of the small number of clinical samples; (2) the resistance of the spinal cord to temozolomide, the first-line chemotherapy drug for brain glioma. Therefore, it is urgent to clarify the research status and potential direction of spinal cord astrocytoma to provide clues for improving its clinical efficacy. Here, we comprehensively reviewed the clinical features, pathological classification, molecular characteristics, current treatments, and ongoing studies of spinal cord astrocytoma. In conclusion, the incidence of spinal astrocytoma is less than 1/10 of brain diffuse gliomas. Although spinal cord astrocytoma has younger age than brain hemisphere diffuse glioma, it mainly occurs in adults which is unlike diffuse brain stem gliomas. According to histological phenotype, spinal cord astrocytomas are divided into astrocytoma and glioblastoma. Almost all patients are IDH wild-type, and a high proportion of patients carry the H3 K27M mutation (about 40%). For WHO grade 2/3 patients, maximal surgical resection was associated with a better prognosis, but for WHO grade 4 patients, the prognosis was associated with histological grade, preoperative spinal cord function, and NLR (peripheral blood neutrophil to lymphocyte ratio). Currently, there is no effective treatment for spinal cord astrocytoma other than radiotherapy. Studies on molecular targeted therapy and immunotherapy have brought new hope for spinal cord glioma, but the lack of effective experiment models has limited their progression. Studies in large clinical cohorts, the development of cell and animal experiment models, and the usage of novel study approaches (such as single-cell technology) should be performed as soon as possible on the spinal cord astrocytoma to improve its precision diagnosis and therapy.

Abstract:Transmembrane protein 63 (TMEM63A) is a mechanosensitive ion channel (MSC) that plays an important role in the process of myelination. TMEM63A was identified as the causative gene of hypomyelinating leukodystrophy 19 (HLD19) in 2019. Myelin is a structure formed by oligodendrocytes in the nervous system, which has both nutrient axons and accelerated action potential conduction. Myelin dysfunction can be manifested as hypomyelination, demyelination and myelin vacuolization. Myelin is rich in lipids, and different lipids are involved in important processes such as myelination, repairment and recognition of glial cells and axons. HLD19 caused by TMEM63A variants is a hypomyelinating disease. TMEM63A variants can cause changes in osmotic pressure, and TMEM63A transmembrane protein on cells can be mechanically stimulated to generate electric current, thus affecting oligodendrocyte differentiation and maturation, resulting in abnormal myelination. At the same time, TMEM63A variations can also cause abnormal distribution of cell membrane lipids, affecting the normal function of lipids. Abnormal lipids by participating in different myelination links eventually lead to myelination disorders.

Abstract:Alzheimer’s disease (AD) is an unremitting neurodegenerative disorder. Astrocytes play a fundamental role in maintaining the health and function of the central nervous system and memory. The pathological changes in brain of AD are closely related to astrocytes. Increasing evidence indicates that astrocytes undergo both cellular and molecular changes at an early stage in AD. Physical activity can effectively relieve cognitive impairment by regulating astrocytes in AD. In this review, we have summarized the multiple improvement effects on AD by physical activity through the regulation of astrocytes, including improving cell morphology and regulating astrocytes activation, increasing the release of trophic factors, regulating astrocytes phenotype and reducing neuroinflammation, improving glucose and lactate transportation in the brain as well as degrading oxidative stress. The knowledge of this review will pave the way for the prevent and treatment of AD through understanding the mechanisms of the beneficial effects mediated by physical activity through regulating astrocytes in AD.

Abstract:Astrocytes play important roles in maintaining the homeostasis of brain, including the maintenance of brain’s water balance. However, under various diseases such as ischemic stroke, astrocytes are the first to show significant cellular edema, which in turn promotes the development of cerebral edema and aggravates brain injury. Regulatory volume reduction (RVD) is a compensatory response of astrocytes to rapidly reduce part of their volume in the face of fast swelling. Recent advances have revealed that volume-regulated anion channel (VRAC) and aquaporin (AQP) are key players in the RVD process. VRAC is a heteromers composed of members of the LRRC8 family. During astrocyte fast swelling, VRAC is activated and mediates the rapid transport of anions and organic osmolytes to extracellular space, which is the main driver of RVD. AQP, a six-transmembrane protein, is a selective bidirectional water channel, which is the structural basis for rapid cellular edema in astrocytes and is also the "fast track" for water transport to the extracellular compartment during RVD. Further understanding of the structure and function of VRAC and AQP and their roles in RVD will help to finally understand the mechanism of astrocyte RVD and provide potential targets for the treatment of brain edema.

Abstract:Neurodegenerative diseases are common and incurable diseases that cause great inconvenience to patients’ lives. Astrocytes play an important role in neurodegenerative diseases. In the nervous system of patients with neurodegenerative diseases, damaged glial cells can have toxic effects on the surrounding neurons, causing neuronal dysfunction and thus death. At the same time, some reactive astrocytes produced by the disease can protect neurons, remove harmful substances around neurons, and temporarily slow down the disease progression. This review will discuss the role of astrocytes in some common neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), Alzheimer’s disease (AD), and Parkinson’s disease (PD). The role played by astrocytes in these diseases is summarized, aiming to further promote the progress of research in neurodegenerative diseases.

Abstract:Objective This study aimed to investigate the expression and proinflammation effect of nitric oxide in the edema of astrocytoma.Methods WHO II (10 cases), II-III (7 cases), and IV (10 cases) grade astrocytoma peritumor edema tissues were identified by magnetic resonance imaging (MRI) and collected after surgery. The content of nitrite was detected by Grice reagent; HPLC-MS/MS was applied to identify inflammatory molecules in edema zone (5 cases of each grade); ClusterProfiler, Proteomaps and Metascapedatasets were used to investigate the potential protein network between NO and microenvironment.Results There was NO in astrocytoma and edema zone, and NO in glioma was higher than that in edema zone, which had cytochrome coxidase (COX), heat shock protein (HSP), CD44 antigen (CD44), interleukin-8 (IL-8), interleukin-24 (IL-24), gelsolin (GSN), stress-induced-phosphoprotein 1 (STIP1), mitogen-activated protein kinase 1 (MAPK1), peroxiredoxin (PRDX), protein S100, and superoxide dismutase (SOD). Enrichment analysis demonstrated that proteins in glioblastoma were more involved in anaerobic metabolism than grade II-III astrocytoma, such as glycolysis. More importantly, these proteins were significantly involved in various redox reactions, such as oxidoreductase activity and peroxidase activity among which iNOS, NO, ONOO^- and SOD-1 played a vital role in redox reactions.Conclusion The formation of edema zone around astrocytoma was formed by inflammatory reaction. Astrocytoma cells regulated SOD-1 and other inflammatory molecules by secreting NO to promote the formation of invasive inflammatory tumor microenvironment.

Abstract:Objective Glioma is the most common malignant primary tumor of the central nervous system. Recently, the rapid development of molecular pathology has brought an important influence on the diagnosis and classification of gliomas. The latest version of the World Health Organization (WHO) Classifications of The Central Nervous System Tumors (fifth edition) published in 2021 has introduced more molecular features to guide the diagnosis and classification of gliomas. The aim of this study was to provide evidence of the application of the latest version of WHO classification via comparing the fluences of the latest and the previous version of WHO classifications on tumor diagnosis and prognosis in a clinical cohort.Methods 512 glioma samples were retrospectively included in the cancer genome atlas database. The diagnosis was performed according to the latest (2021 edition) and the previous version (2016 edition) of WHO classifications, respectively. Kaplan-Meier curves were used to calculate median overall survival and analyze survival differences.Results We completed the diagnosis and grading of 512 cases by the latest (2021 edition) and the previous version (2016 edition) of WHO classifications, respectively. 53 cases of IDH mutant tumors and 72 cases of IDH wildtype tumors were upgraded to grade 4 in the latest version (2021 edition) of the WHO classification. These tumors with elevated grades also had a worse prognosis.Conclusion Compared with the previous version, glioma can be classified and graded more accurately by the latest version (2021 edition) of the WHO classification. Diagnosis and grading should be performed according to the latest version as soon as possible.

Abstract:Objective To analyze the clinical features and early diagnosis of leukoencephalopathy with vanishing white matter (VWM).Methods The clinical material and gene sequencing report of one faimily with VWM were retrospectively analyzed, and relevant literatures were reviewed.Results Patient 1, female, 4 years and 10 months old, developed the disease due to abnormal gait. Magnetic resonance imaging (MRI) of the brain showed white matter abnormality with diffuse symmetry. Gene detection revealed two missense mutations in EIF2B4 gene, both located in exon 13, respectively C. 1544 T→A and C. 1445 G→T heterozygous variation, which has not been reported. The other child was her identical sister, whose onset time, manifestations, brain MRI and gene test results were roughly the same. However, after 1-year follow-up, we found that patient 1 degraded faster.Conclusion We found two novel missense mutations C. 1544 T→A and C. 1445 G→T. Early genetic analysis is suggested to make a definite diagnosis for leukoencephalopathy with VWM.

Abstract:Objective To explore the clinical and genetic characteristics of patients with hypomyelinating leukodystrophy caused by TMEM163 mutation, track the natural history of the disease, and to construct patient-derived induced pluripotent stem cells, thus laying the foundation for mechanism research.Methods Clinical and genetic data of two patients (Pt1, Pt2) with TMEM163 mutation were collected from 2009 to 2022 in Department of Pediatrics, Peking University First Hospital. The clinical manifestations, genetic data, and protein structure data were analyzed. Peripheral blood of Pt2 was collected to construct induced pluripotent stem cell (iPSC).Results Clinical features: both patients showed early motor and language development retardation and hypomyelination abnormalities from brain magnetic resonance imaging (MRI), however, the symptoms gradually alleviated; nystagmus was the first symptom, abnormal gait, low muscle tone and mild to moderate developmental retardation were observed in both of them; Pt1 has the same growth and development level as children of the same age at 7 years old. Genetic features: both cases were newly detected missense variants at the same locus of TMEM163 c.227T>G p.(L76R), c.227T>C p.(L76P). The differentiation of iPSC induced by peripheral blood monocytes from Pt2 was consistent with the characteristics of iPSC.Conclusion The follow-up study of 2 children with HLD contributes to the understanding of the natural history of HLD caused TMEM163 mutation, expands the understanding of the clinical phenotype of HLD, and constructs TMEM163 c.227T>C p.(L76P) iPSC, which lays a foundation for the mechanism study.

Abstract:Objective To explore the role of CTSB (cathepsin B)-mediated NLRP3 bodies in arsenic-induced inflammatory activation of mouse microglial BV-2 cell.Methods BV-2 cells in logarithmic growth phase were respectively exposed to NaAsO₂ solution at the final concentration of 0, 2, 4 and 8 μmol/L for 24 h. Cell viability was detected by CCK-8 assay. The levels of intracellular CTSB, NLRP3, Caspase-1, IL-18, and IL-1β were determined by Western blot. The intracellular lysosome level was detected by flow cytometry analysis. According to the experimental results, CTSB inhibitor group (5 μmol/L CA074-Me+8 μmol/L NaAsO₂,10 μmol/LCA074-Me+8 μmol/L NaAsO₂) was added to detect the expression of NLRP3, Caspase-1, IL-1β and IL-18 in the two groups.Results Compared with the control group, the cell inhibition rate of all exposed groups increased in a dose-dependent manner, the level of lysosome integrity decreased, the difference was statistically significant (P<0.01). The expression of CTSB, NLRP3, IL-1β and IL-18, Caspase-1 increased significantly, the difference was statistically significant (P<0.01). Compared with the inhibitor group, the intracellular CTSB, NLRP3, IL-1β and IL-18, Caspase-1 levels of BV-2 cells exposed to 8 μmol/L NaAsO₂ without inhibitor were significantly higher (P<0.01).Conclusion NaAsO₂ can induce the increase of CTSB level in microglia, mediate the activation of microglia by NLRP3 inflammatory bodies, promote the release of inflammatory factors and damage the central nervous system.

Abstract:Objective Neuroglobin (Ngb) has been described as a neuroprotective agent in cerebral ischemia, which has a high affinity for oxygen and helps to prevent hypoxic-ischemic brain damage, and to affect the outcomes after acute ischemic stroke (AIS). In this study, the changes of serum Ngb level after AIS were investigated and the relationship of Ngb and stroke severity and prognosis were evaluated.Methods We prospectively measured the serum levels of Ngb in AIS patients at different time points (within 72 h and on day 14 (D14) after onset of cerebral infarction) and in control subjects. Serum Ngb levels were compared between the AIS patients and controls. The serum Ngb levels in the AIS patients with and without diabetes mellitus (DM) were also compared. Correlations between Ngb level and infarct size and that between Ngb level and National Institutes of Health Stroke Scale (NIHSS) score of the patients were analyzed. Receiver operating characteristic (ROC) curve was used to appraise their value in predicting the outcome at day 90 after AIS, which was evaluated using the modified Rankin Scale (mRS).Results Serum Ngb levels in patients were 105.7 (88.3, 123.1) μg/L within 72 h and 72.8 (58.7, 86.9) μg/L on D14 after cerebral infarction, respectively. Serum Ngb level in control group was 58.2 (35.0, 81.6) μg/L. Serum Ngb level within 72 h after AIS increased significantly compared with that in the control group (P<0.05). Serum Ngb levels of AIS patients with or without DM showed no significant difference within 72 h and on D14 after AIS (P>0.05). Serum Ngb level within 72 h was significantly correlated with NIHSS score (Spearman correlation coefficient=0.232, P=0.038). Serum Ngb levels had no significant difference in patients with large infarction than in those with small or moderate infarction at each time point (P>0.05). ROC curve analysis suggested that the serum Ngb level had a significantly good predictive power for outcomes.Conclusion The results indicated that serum Ngb level increased within 72 h after AIS, which is independent of comorbidity with diabetes. Serum Ngb level within 72 h was significantly correlated with NIHSS score, and Ngb might have the potential to be a predictor of stroke severity and prognosis.

Abstract:Objective Human astrocytes and human neurons were transfected with EIF2B5-RNAi vectors or blank as cell model to investigate the causes that white matter glial cells selectively involved in vanishing white matter disease.Methods Apoptosis and cell viability were measured in human astrocytes and neurons with EIF2B5-RNAi or blank vector before or after the stimulation of endoplasmic reticulum stress (ERS). The sequence of known and unknown microRNAs was performed to screen those participated in regulating the response of ERS.Results Under the baseline condition, apoptosis rates were detected higher in human astrocytes with EIF2B5-RNAi and cell viability decreased significantly than the wild-type and neurons. More pieces of miRNAs regulated the ERS rescue in astrocytes with blank vectors than the EIF2B5-RNAi group. In the cluster analysis, 5 pieces of miRNAs were identified as key components in pathway network.Conclusion The recovery of human astrocytes from ERS may be more dependent on the numerous miRNAs than neurons for cell proliferation and differentiation. The eroded clusters of miRNAs may promote spontaneous apoptosis and cell viability decrease in human astrocytes with EIF2B5-RNAi. As a result, it reduced the chance of survival in human astrocytes with EIF2B5-RNAi after ERS crisis.

Abstract:Objective Moxibustion is a classic traditional Chinese medicine treatment that combines physical therapy (hyperthermia) and chemical therapy. It has been shown to have an inhibitory effect on a variety of cancers, but the cellular biological mechanism is still unclear. This study aims to study the effect of hyperthermia on astrocytic cancer cell line U251, and to reveal the effect of moxibustion on cancer cells through hyperthermia.Methods The morphological changes of U251 cells treated with hyperthermia at 42℃ for 108 h were recorded by microphotography. The changes of total cell number, live cell number and live cell proportion were detected by cell counting after 3 d of hyperthermia to evaluate the effects of hyperthermia on cell proliferation and death. The effect of hyperthermia on cell apoptosis was evaluated by detecting Annexin V and Caspase-3.Results Hyperthermia significantly inhibited cell proliferation and increased cell death. Compared with the control group, the U251 cells treated with hyperthermia had obvious nuclear pyknosis, and Annexin V and PI markers were significantly increased, indicating that the cell death caused by hyperthermia was mainly caused by Caspase related apoptosis.Conclusion This study demonstrated that hyperthermia can inhibit cell proliferation and induce Caspase related apoptosis in astrocytic cell line U251.